One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

You will be able to figure out when to plant heliotrope by reviewing the USDA zone info for Petersburg.

Planting Calendar for Heliotrope

Frost tolerance for heliotrope:	Not tolerant of frost.
When to plant:	After the last frost when the weather gets warmer.

Heliotrope do not do well in cold weather which means that it's important to wait until it warms up after the last frost before you can plant them.

The earliest that you can plant heliotrope in Petersburg is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant heliotrope and expect a good harvest is probably August. Any later than that and your heliotrope may not have a chance to fully mature. If you are starting your heliotrope indoors then you might be able to get away with starting them a couple of weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Petersburg. It might get as low as 5°F during the coldest months of winter.

It's important to remember that the actual date of last frost is not always accurate because it is based on the USDA zone info for Petersburg and it can change quite a bit from year to year. Half of the time in Petersburg you get surprised by a frost after April 15 so make sure that you are ready to cover your heliotrope if you have one of those late frosts.

USDA Zone Info for Petersburg

Here is the info for USDA Zone 7b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	5°F
Highest Expected Low	10°F

This means that on a really cold year, the coldest it will get is 5°F. On most years you should be prepared to experience lows near 10°F.

Plants to Grow in Petersburg

You may be interested in your other planting guides for Petersburg.